Constants used to implement thin locks.
A portion of a word, either in the object header
or in some other location, is used to provide light weight
synchronization operations. This class defines
how the bits available for thin locks are allocated.
Either a lock is in fat state, in which case it looks like
1Z..Z where Z..Z is the id of a heavy lock, or it is in
thin state in which case it looks like 0I..IC..C where
I is the thread id of the thread that owns the lock and
C is the recursion count of the lock.
JavaHeader.NUM_THIN_LOCK_BITS = # of T's
JavaHeader.THIN_LOCK_SHIFT = # of b's